Recently, with the increasing progress of science and technology, humanization is gradually realized in operation interface of a variety of electronic products. For example, through a touch panel, a user can directly operate on a screen, input information, texts and designs by a finger or stylus, without the trouble of using an input device such as keyboard or keys. Actually, the touch panel is usually composed of a sensing panel and a display disposed behind the sensing panel. An electronic device judges the meaning of the touch based on the position touched by the user on the sensing panel and the screen presented by the display at the time, and executes a corresponding operation result.
Capacitive touch technology judges a touch event by sensing the change of capacitance of a detection capacitor in a detecting circuit. The existing capacitive touch technology can be divided into a self-capacitance technology and a mutual-capacitance technology. A capacitance sensing circuit in a self-capacitance touch panel or a mutual-capacitance touch panel can apply a periodic input signal to the detecting circuit and receive an output signal from the detecting circuit, calculate the change amount of the detection capacitor in the detecting circuit by analyzing a phase or amplitude of the output signal, so as to judge the occurrence of a touch event and the actual coordinate position.
However, since the input signal has a specific frequency, when the capacitance sensing circuit of the touch panel is very close to a liquid crystal display module, a charging module, or other devices, it is susceptible to electromagnetic interference of specific frequencies from the surrounding liquid crystal display module, the charging module or other devices. In the related art, an input signal of the capacitance sensing circuit does not undergo any process to be synchronized with signals of the liquid crystal display module, the charging module or other devices, such that external electromagnetic interference brings a negative impact on the capacitance sensing circuit judging the touch event. Therefore, there is a need for improvement in the related art.